﻿/*
*    Qizx/open 3.0 beta
*
* This code is the open-source version of Qizx.
* Copyright (C) 2004-2009 Axyana Software -- All rights reserved.
*
* The contents of this file are subject to the Mozilla Public License 
*  Version 1.1 (the "License"); you may not use this file except in 
*  compliance with the License. You may obtain a copy of the License at
*  http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
*  WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
*  for the specific language governing rights and limitations under the
*  License.
*
* The Initial Developer of the Original Code is Xavier Franc - Axyana Software.
*
*/
using System;
using EvaluationException = System.Qizx.Api.EvaluationException;
using EvalContext = System.Qizx.XQuery.EvalContext;
using ExprDisplay = System.Qizx.XQuery.ExprDisplay;
using Focus = System.Qizx.XQuery.Focus;
using ModuleContext = System.Qizx.XQuery.ModuleContext;
using XQType = System.Qizx.XQuery.XQType;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace System.Qizx.XQuery.Op {
    class BlockExpr : Expression {
        public Expression body;     // return expr
        private Expression[] clauses = new Expression[0];

        public BlockExpr() {
        }

        public VarClause addClause(LetClause clause) {
            clauses = addExpr(clauses, clause);
            return clause;
        }

        LetClause getClause(int rank) {
            return rank < 0 || rank >= clauses.Length ? null
                    : (LetClause)clauses[rank];
        }

        public override Expression Child(int rank) {
            if (rank < clauses.Length)
                return clauses[rank];
            rank -= clauses.Length;
            if (rank == 0)
                return body;
            return null;
        }

        public void dump(ExprDisplay d) {
            d.header(this);
            d.children(clauses);
            d.child("body", body);
        }

        public override int getFlags() {
            return body.getFlags();
        }

        public Expression staticCheck(ModuleContext context, int flags) {
            LocalVariable mark = context.latestLocalVariable();

            // for and let clauses, declare local variables
            for (int c = 0; c < clauses.Length; c++) {
                context.staticCheck(clauses[c], 0);
            }

            // returned expression:
            body = context.simpleStaticCheck(body, 0);
            type = body.getType().itemType().star;

            context.popLocalVariables(mark);
            return this;
        }

        // -----------------------------------------------------------------------------

        public override XQValue eval(Focus focus, EvalContext context) {
            for (int c = 0; c < clauses.Length; c++) {
                LetClause init = getClause(c);
                if (init.expr != null)
                    context.storeLocal(init.varDecl, init.expr, null, false,
                                       focus, context);
                else
                    context.storeLocal(init.varDecl.address,
                                       XQValues.Empty, false, null);
            }

            return body.eval(focus, context);
        }

    }
}